1. Field of the Invention
The present invention relates to a brushless motor.
2. Related Art
A known outer rotor type brushless motor includes a rotor housing formed in a bottomed cylinder shape, a center piece that faces an opening of the rotor housing, and a ring shaped stator core that is press-fitted into the outside of a cylinder shaped portion formed to the center piece and that is housed inside the rotor housing (see for example Japanese Patent Application Laid-Open (JP-A) No. 2009-148056).
In such as brushless motor, in a case in which the center piece and the stator core are formed from different materials to each other, there is a concern of a gap being formed in the radial direction between the cylinder shaped portion of the center piece and the stator core due to their different linear expansion coefficients. In particular, since shrinkage of the stator core and the center piece occurs mainly in the radial direction, a gap is easily formed with even a small amount of shrinkage.
In a case in which a gap has formed in the radial direction between the cylinder portion of the center piece and the stator core, there is a concern of water that has entered through an axial direction gap between the rotor housing and the center piece passing through the gap that has formed in the radial direction between the cylinder shaped portion and the stator core, and penetrating through to inside a bearing housing portion at a central portion of the rotor housing. When this occurs, there is a concern of a bearing housed inside the bearing housing portion being exposed to water, leading to rusting of the bearing.